**By R. Belmans**

**The inverse problem,** to calculate a current density distribution for an imposed magnetic field can be obtained by using an in-plane formulation. Applying the Maxwell equation (3.8) and using the magnetic scalar and electric vector potential yields a particular

**Finally the in-plane****valid in the time domain, is described by:**

**In the frequency domain, by assuming a sinusoidal magnetic field and substituting****it can be written:**

This formulation is very similar to the A-formulation of the magnetic field and can be solved with the same methods. This formulation can not be applied to non-conducting regions. There,

must be evaluated.